Title

Dairy Curds

Problem Scenario

Broad Question

What dairy product curdles most?

Specific Question

How does the percentage of fat in dairy products affect the rate it curdles at and the amount of curds it produces

Hypothesis

It is hypothesized that the heavy cream will produce the most curds.

Graph of Hypothesis

Variables

Independent Variable:

Percent of milk and type of half and half

Dependent Variable:

amount of curds

Variables That Need To Be Controlled:

amount of dairy product, amount of time, temperature of storage area, containers milk curdles in, brand of dairy product, scale, cheesecloth

Vocabulary List That Needs Explanation

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General Plan

This experiment was conducted to determine what dairy product produces the most curds. The general plan for the experiment was to make 3 glasses of 1 cup each of the following dairy products: skim milk, 1% milk, 2% milk, whole milk, fat free ½ & ½ , regular ½ & ½ and heavy cream. The cups sat together in the boiler room at school, in one cardboard box with a lid. After one week of time, one cup of each liquid was drained and the amount of curds was then measured by dumping the contents of the cup through a cheesecloth and into a bucket, separating the curds and whey. The remaining curds were then weighed on a scale, and the data was recorded. After another week, two weeks in total, the process was repeated with the second cup. And after three weeks, the same was done with the final cups. Each dairy product was then graphed to see which dairy product produced most curds and to compare the rates and amounts. The amounts of curds produced was determined by adding all three week’s curds to create one weight.

Potential Problems And Solutions

Safety Or Environmental Concerns

Experimental Design

(add the correct headings from the experimental design page before beginning)

Resources and Budget Table

Material	Size	Description	Quantity	Gotten From	Cost
container of skim milk	Gallon	My Essentials	1	Hannafords	2.45
container of 1% milk	Gallon	My Essentials	1	Hannafords	2.50
container of 2% milk	32 oz / quart	Hood	1	Hannafords	1.59
container of whole milk	32 oz / quart	My Essentials	1	Hannafords	1.45
container of fat free half & half	32 oz / quart	My Essentials	1	Hannafords	2.29
container of regular half & half	32 oz / quart	My Essentials	1	Hannafords	2.19
container of heavy cream	16oz	My Essentials	2	Hannafords	2.49 each
cheesecloth	36” by 3 yards	Dritz	1	Walmart	2.97
Plastic Cups	16oz	Great Value	24 pack	Walmart	1.28
scale	measures in grams	1	Borrow from Mr. Yahna	Free
Box	large enough to hold 21 cups	cardboard, with a lid	3	Available	Free
Bucket	gallon bucket	plastic with no holes	1	Available	Free
Tray	big enough to hold cheesecloth	plastic	1	Available	Free
Bungee Cord/Rubber Band	needs to fit around bucket	1-2	Available	Free
masking tape	roll	1	Available	Free
sharpie	thick pen	black	1	Available	Free

Data Table

Time Line

Wednesday February 29 : Complete Design (home)
Friday March 2 : All Materials Collected and test run of set up (home and jbes)
Monday March 5 : Start experiment (come in early, do it in the morning)
Monday March 12 : First week data collection (jbes,morning)
Monday March 19 : Second week data collection (jbes, morning)
Monday March 26 : Third week data collection, finish experiment (jbes, morning)
Friday March 30 : Complete results and conclusions (home)

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Background Research

Curdling

• curds are dairy products
• curds are gotten by curdling milk and draining away the liquid part
• curds are made from the milk proteins combining to make a solid
• the liquid part left is the whey
• milk is made of two main proteins - whey and casein
• casein protons for the curd, solid
• whey proteins for the remaining liquid
• curdling is often done using rennet or other acidic products such as vinegar and lemon juice
• curds are used often in the making of cheese, as well as custards,sauces and tofu
• curdles when a sour substance touches it
• lactic acid is created and milk sours and curdles
• when milk is stored for a long time, bacteria in the milk becomes harmful
• Also no clotting occurs above 60° to 65°C.
• The clot is softer at low temperatures
• tougher and stringy at high temperatures.
• could upset stomach if curdled milk is drank
• To change into curd. (definition)
• curdles happen when casein molecules aggregate or group

Milk

• Protein (casein) in milk causes it to curdle
• The composition of one serving of milk (whole dairy milk w/ 3.25% fat) includes:

Overall Composition:

Water: 215.50 g
Energy: 146 kcal
Carbohydrate: 11.03 g
Fat: 7.93 g
Protein: 7.86 g
Minerals (Ash): 1.68 g

Vitamins

Vitamin A: 68 µg
Thiamin (Vitamin B1): 0.107 mg
Riboflavin (Vitamin B2): 0.447 mg
Niacin (Vitamin B3): 0.261 mg
Pantothenic Acid (Vitamin B5): 0.883 mg
Pyridoxene (Vitamin B6): 0.088 mg
Cobalamin (Vitamin B12): 1.07 µg
Vitamin C: 0.0 mg
Vitamin D: 98 IU
Vitamin E: 0.15 mg
Folate: 12 µg
Vitamin K: 0.5 µg

Minerals (Ash):

Calcium: 276 mg
Copper: 0.027 mg
Iron: 0.07 mg
Magnesium: 24 mg
Manganese: 0.007 mg
Phosphorus: 222 mg
Potassium: 349 mg
Selenium: 9.0 µg
Sodium: 98 mg
Zinc: 0.98 mg

whey makes up 20% of the protein in milk by weight

Pasteurized Milk

• for this experiment we will be using different percents of cow milk that has been pasteurized
• pasteurization is a process that involves heating the milk to a certain temp for a certain length, and then cooling it immediately
• this process slows microbial growth in the food
• is not intened to kill all micro-organisms in food
• it reduces the number of pathogens so the milk is less likely to cause disease
• (pathogens are germs)
• some dairy products may be superheated to make sure that all pathogens are destroyed
• cream was pasteurized to help keep butter fresh
• pasteurizing milk helps it to last longer
• regular pasteurized milk lasts about two to three weeks
• ultra-pasteurized milk can last much longer, two to three months
• there are two main types of pasturization:

-Hight Temperature Short Time (HTST)
this helps to extend shell life (esl) meaning it helps to make it last longer
-Ultra High Temperature (UHT)

• pasteruization uses temps under boiling
• at boiling, casein molecules group together, or curdle

References

__http://en.wikipedia.org/wiki/Curd__
__http://en.wikipedia.org/wiki/Curdling__
__http://chestofbooks.com/food/science/Experimental-Cookery/Coagulation-Of-Milk.html#ixzz1mJJQpGzH__
__http://www.thefreedictionary.com/curdled____http://wiki.answers.com/Q/What_is_cow_milk_made_of#ixzz1mURwkDMV__
__http://en.wikipedia.org/wiki/Pasteurization__
__http://www.sritweets.com/milk-curdle-milk-curdle-bacteria-present-milk/__

Detailed Procedure

1. Gather all of our materials.
2. Bring materials to boiler room.
3. Pour each type of dairy product into it’s own separate cup, three cups for each dairy product.
4. Label each cup with product and week using the tape and sharpie.
5. Place all full cups for week one into a cardboard box.
6. Use tape and sharpie to label box “week one” on both the lid and side.
7. Place all full cups for week two into a second cardboard box.
8. Label this box “week two” on lid and side using sharpie and tape.
9. Put all remaining cups (for third week) into the third box.
10. Label this box “week three” with the sharpie and tape on both the lid and side.
11. Cover all of the boxes and line up on the side of the boiler room wall.
After one week of time...
12. Wash the cheesecloth with water, and wring out so its only damp (not dripping wet, but not dry).
13. Take one cup out of the “week one” box.
14. Have one person hold cheesecloth over a bucket while the other person dumps cup through it. Make sure the cheesecloth is taut, you might need a rubber band or bungee cord to do this.
15. Leave or hold the cheesecloth stretched taut over the bucket for 2 minutes, allowing whatever liquid (whey) to drip into the bucket.
16. After 2 minutes of time, place cheesecloth with curdles onto tray and then onto scale. 17. Record the weight in grams.
Question on weighing - do we average scale before, subtract weight of cheesecloth & tray or leave the two weights in because it will be the same with all weights
18. Record the data in a notebook, being sure to include week, dairy product and weight in grams.
19. List any observations in the notebook as well. Include things like appearance, smell, comments on the process, problems or difficulties, etc.
20. Take a picture of curds as well as a few of the process.
21. Wash cheesecloth like before. Rinse in water, making sure all debris from last product is off. Wring it out so it is only damp.
22. Repeat steps 13 through 21 with each cup in the “week one” box.
23. After another week of time, 14 days in total, repeat steps 12 through 21. This time use the cups from the box labeled “week two”.
24. After a third week of time, 21 days in total, repeat steps 12 through 21. This time use the cups from the box labeled “week three”.

Diagram

Photo List

All dairy products first day
All dairy products after one week
All dairy products after two weeks
All dairy products after three weeks
boxes in boiler room with lid on and off
curdles on scale
pouring milk into cheesecloth
washing cheesecloth
recording date in notebook
close up of curds

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Results

All Raw Data

Graphs

Photos

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Data Analysis

Conclusion

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Discussion

Benefit to Community and/or Science

Abstract